Synthesis of S-shaped polycyclic aromatic hydrocarbons as anthracene-fused double expanded helicenes by intramolecular alkyne cycloisomerization
Bibliographic record
Abstract
Polycyclic aromatic hydrocarbons [3]DHA and [5]DHA with three and five fused anthracene units, respectively, were synthesized as expanded helicenes with two helical sites. Double intramolecular alkyne cycloisomerization of diaryldiethynylbenzene precursors with PtCl 2 catalyst produced the desired compounds. The X-ray crystallographic analysis of cocrystals of [3]DHA and [5]DHA with C 6 F 6 revealed that these compounds have S-shaped aromatic frameworks deformed into nonplanar C i symmetric structures, designated as ( M/ P)-[3]DHA and ( M, M/ P, P)-[5]DHA based on the helicity of the two helical moieties. The density functional theory calculations suggested that these forms are less stable than the C 2 symmetric global minimum structures, ( P/ P)-[3]DHA and ( P, P/ P, P)-[5]DHA. The calculated barriers to interconversion between possible structures by helical inversion were 22 and 40 kJ mol –1 for [3]DHA and [5]DHA, respectively. 1 H NMR, UV-vis, and fluorescence spectra of these aromatic compounds are compared with those of the corresponding single expanded helicenes.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".